There is a continuing need to further improve the thermal efficiency of conventional water heaters, as thermal efficiency improvements facilitate energy conservation and represent cost savings to the end user. In an effort to improve thermal efficiency, it is generally beneficial to maintain a substantially uniform water temperature within the water heater tank. However, the water temperature tends to be cooler near the bottom of the water heater tank and rises as the water level approaches the top of the water heater tank. In other words, as a result of thermal currents within the water heater, the thermal energy is driven towards the top of the water heater tank. This phenomena, commonly known as stacking or thermal stratification, has an adverse impact on the energy efficiency of a water heater.
Thermal stratification within a water heater tank decreases a water heater's First-Hour rating, which is a measure of the volume of hot water a water heater can supply in a one-hour time period. The First-Hour rating is an industry-wide indicator used to establish the thermal efficiency of a water heater. Water Heater manufacturers continually strive to increase the First-Hour rating.
Improvements have been made in this regard. For example, improved water heater systems are disclosed in U.S. Pat. No. 5,341,770, which illustrates a water heater cold water inlet deflector means which can create turbulent flow within the inlet conduit and create turbulent water circulation throughout the water storage tank so that sediment is disturbed and suspended, stacking is prevented and efficiency is improved.
Nevertheless, there continues to be a need to further reduce thermal stratification within a water heater tank to improve the thermal efficiency of water heaters and/or to reduce the impact of any such thermal stratification.